Process analytic systems are used in a variety of industries to measure process characteristics in substantially real-time. Such industries include the chemical, petrochemical, pipeline, and pharmaceutical industries. Process analytic systems are often used for process gas analysis, combustion analysis and control, and emissions monitoring in any of the above industries.
Process analytic systems differ substantially from laboratory analyzers in the manner in which sample handling is effected. For example, samples are usually held as a gas or liquid in an appropriate container that is transported, sometimes by hand, to a laboratory analytical instrument. In contrast, the process analytic system receives its sample directly from a sampling point in the process, without human assistance. Process analytic systems can include a process analyzer and a process sample handling system.
For a process analyzer in a process analytic system, such as a process gas chromatograph, to provide an accurate analysis of the process, it is important to convey the sample from the process to the analyzer such that the sample is representative of the process. Since any number of variables can affect the extent to which the sample represents the process, it is desirable to control many variables including temperature, pressure and flow while conveying the sample to the analyzer. Further complicating matters is the fact that the sample may be quite hot and under considerable pressure, contain water vapor, solids, condensed liquid, etc. One example of a known process analyzer is the Continuous Analyzer Transmitter, available from Rosemount Analytical, Inc., of Anaheim, Calif. Another example of a known process analyzer is the Model GCX Process Gas Chromatograph, available from Rosemount Analytical, Process Analytic Division, of Orrville, Ohio.
A process sample handling system is utilized in a process analytic system to extract a process sample from a sampling point and convey the sample to a process analyzer. Generally, the sample handling system includes all requisite components to maintain a constant sample flow to the analyzer. Thus, the sample handling system generally includes suitable pressure reduction components, filters, vaporizers, flow controls, and sample switching or selector valves for introducing multiple sample streams or a calibration standard to the process analyzer. With the exception of vaporizers, filters, and pressure reducers, most components of the sample handling system are usually located near the process analyzer, and sometimes within the same housing as the analyzer.
The process sample handling system is an important component of an effective process analytic system. If the process sample is not delivered to the process analyzer in a condition that is representative of the process, errors will occur in the analysis. Many of the problems encountered in process analytic systems can be traced to a problem occurring in the process sample handling system.
Individual process applications are each relatively unique. The combination of process fluid pressure, temperature, flow, chemistry and other factors contribute to the uniqueness of a given process. In order to facilitate effective process analysis, process sample handling systems have been designed for specific process applications. This is done once information about a specific process application is known. Although such specific tailoring reduces error in the process analytic system, it requires additional manufacturing time since a custom system must be built for each application. Additionally, significant field installation time is generally required for system commissioning.
As industrial process analysis and control becomes more sophisticated there is an increasing need to provide a process sample handling system for a process analytic system that does not need to be manually customized, either by manufacturing or by commissioning, for each application.